void GridGameMain::drawGrid() {

    int gridSquareSize = 20;
    int gridWidth = ui->gridView->width() - gridSquareSize;
    int gridHeight = ui->gridView->height() - gridSquareSize;
    QPen gridPen(Qt::white); // grid color
    for (int x = 0; x <= ui->gridView->width(); x += gridSquareSize) {

        scene->addLine(x, gridSquareSize, x, gridHeight, gridPen);

    }

    for (int y = 0; y <= ui->gridView->height(); y += gridSquareSize) {

        scene->addLine(gridSquareSize, y, gridWidth, y, gridPen);

    }

}